NEC3 ECSC: What Completion Date is used under Clause 60.1(10) of the ECSC

Clause 60.1(10) of the ECSC is as follows:

The Contractor is prevented by weather from carrying out all work on the site for periods of time, each at least one full working day, which is in total more than one-seventh of the total number of days between the starting date and the Completion Date. In assessing this event, only the working days which exceed this limit and on which work is prevented by no other cause are taken into account.”

I am assuming that it is always the Completion Date in CD Part 1 that is used in this calculation even if the Completion Date has subsequently changed.

Is this correct?

Completion Date is a defined term which refers to the ‘completion date’ (identified term) which can be changed in accordance with the contract, so the ‘changed’ Completion Date would be used.

There are possible injustices with the practical application of this clause, such as changing the Completion Date beyond the Christmas and New Year period when no ‘working days’ are occurring, but this time is still taken into account when assessing a calculation… Hopefully a pragmatic view is adopted and applied, including the definition of a ‘full working day’.